Information relating to the operation of traffic control signals may be useful in various contexts. Methods and systems have previously been proposed in which information or recommendations are provided to drivers based upon information relating to the operation of traffic control signals, e.g. traffic lights. In some methods, information may be provided to drivers regarding the state of upcoming traffic control signals, e.g. along a route being navigated. The information may be used to provide a speed recommendation to drivers. For example, a driver may be advised as to an appropriate speed of travel to enable them to arrive at a traffic control signal in order to coincide with a green phase of the signal, i.e. to ride a “green wave” through a series of traffic control signals. Information about the operation of traffic control signals may be used to advise as to appropriate speeds of travel to enable a driver to travel through a region containing one or more sets of traffic control signals in a more efficient manner, in terms of travel time and/or fuel usage. Knowledge of traffic control signal operation is also useful in determining more accurate travel times, e.g. by navigation devices, or for infrastructure planning, etc, and in optimising routes, e.g. with respect to travel time.
Information about the operation of traffic control signals has previously often relied upon traffic control signal operation data obtained from third party sources (e.g. governmental traffic sources). Such data may often be based upon data collected from fixed traffic sensors in the vicinity of traffic control signals. Techniques of this type offer limited flexibility in terms of the data available and the traffic control signals for which data is provided, and are relatively expensive to implement, requiring the appropriate fixed infrastructure to be in place.
WO 2013/060774 A1 entitled “Methods and Systems for determining information relating to the operation of traffic control signals” describes methods of determining information relating to the operation of a traffic control signal using positional data relating to the movement of vehicles with respect to time along a path controlled by the traffic control signal (so-called vehicle “probe” data). The application describes methods by which the probe data may be used to predict future transition times between phases of the traffic signal. A cycle time for the signal may be derived.
The Applicant has realised that there remains a need for further methods and systems for determining information relating to the operation of traffic control signals, and which, in particular, although not exclusively, may be used to determine information relating to the operation of traffic control signals which do not operate in accordance with a predetermined cycle plan having phase durations that are set in advance. Such traffic control signals may be referred to as “dynamically managed” traffic control signals, and operate in accordance with cycles in which the durations of different phases are variable, usually between predetermined upper and lower limits. The durations of the phases may typically be variable in response to demand, e.g. based on the actual traffic conditions at an intersection where the signal is located. For example, where there is a large quantity of traffic wishing to follow a particular path through the signal, the duration of a phase of the traffic control signal permitting traffic flow along that path may be increased to permit the passage of a greater number of vehicles per cycle. Traffic control signals may be dynamically managed in various manners. For example, the traffic control signals themselves may be arranged to sense demand on the approach to the signal, e.g. queuing traffic, or alternatively or additionally traffic control signals may communicate directly with approaching vehicles to sense their presence. In other arrangements, traffic control signals may alternatively or additionally be managed remotely through communication with a traffic management centre, e.g. through wireless or wired infrastructure, in a manner responsive to demand. It will be appreciated that determining information relating to the operation of such dynamically managed traffic control signals may present particular challenges due to the inherent unpredictability of their operation.